Eta-plane hinge joint



m 1957 J. c. CROWLEY 2,805,401

H-FLANE HINGE JOINT Shets-Sheet l Filed Nov. 24, 1 953 INVENTOR J. C.CROWLEY A TTORNEV Sept 3, 1957 J. c. CROWLEY 1 H-PLANE HINGE JOINT FiledNov. 24, 1953 2 Sheets-Sheet 2 1 V 17W \W Y v INVENTOR J. C. CROWLEY AT'TORNEV H-PLANE HINGE JOINT Application November 24, 1953, Serial No.394,102

6 Claims. (Cl. 333-98) This invention relates to Wave guide structuresand more particularly to a magnetic or H-plane hinge joint forrectangular wave guides.

Hinge joints are often employed in electronic systems involving waveguides to permit relative movement of one apparatus component withrespect to another while permitting electrical interconnection betweenthe components for the transmission of microwave energy. Perhaps themost important application of such hinge joints is found in radar andsimilar systems wherein an antenna arranged for scanning motion must beinterconnected with a stationary microwave radio transmitter.

In this and other applications the dual problem exists of on the onehand, providing adequate angular movement of one wave guide with respectto the other and on the other hand, preventing inefiicient transfer ofmicrowave energy through the joint. These problems have been solved withgreater or less success by numerous types of wave guide joints whereinlimited relative motion is provided. In certain of these joints a chokeis provided for the purpose of reducing leakage of energy from thejoint. In general such chokes are satisfactory only when the wave guidesare in alinernent. When in such structures the guides are relativelyrotated about the hinge axis the dimensions of the choke vary and thechoke is rendered substantially less efiective. Higher standing waveratios and greater energy leakages result.

It is the object of the present invention to provide an H-plane hingefor rectangular wave guide structures capable of relatively largeangular motion without lIltlOdllC-.

ing undesirable standing wave within the guides or leakage of thetransmitted energy from the joint.

In accordance with the above object there is provided a wave guide hingejoint in which two rectangular guides are provided for relative angularmovement about an axis normal to an H-plane common thereto. Platesmounted on and spaced from the opposite wide sides of one guide arearranged for interleaving engagement with a pair of slotted jaws mountedon the opposite wide sides of the other guide. The plates and jawsrespectively are overlapped sufficiently to cover the gap between theends of the wave guides for a desired range of angular movement and arepinned together to permit such movement. The inner walls of the slots inthe jaws on the second guide extend beyond the axis and into the spacebetween the side plates and the first guide to form half-wave chokesextending across the opposite wide sides of the wave guides to providewave continuity between the guide sections and prevent leakage from thejoint.

The above and other features of the invention will be described in thefollowing detailed specification taken in connection with the drawingsin which Fig. l is a perspective view of an H-plane hinge according tothe invention, partially broken away to show certain details of thejoint and with certain elements thereof shown in exploded form tofacilitate understanding of the invention;

rates Patent Patented Sept. 3, 1957 movement about an axis aa' normal toan H-plane com-.

mon to the two wave guides. For this purpose paired jaws 14 best shownin Fig. 2 of the drawings are formed on the opposite wide sides of thesecond wave guide 12. Similarly paired side plates 16 shown in Fig. 2 ofthe drawings are mounted on and spaced from the wide sides of the firstwave guide 10. The jaws 14 and side plates 16 are dimensioned forinterleaving engagement, with the side plates 16 extending into slotsdefined by the jaws 14 and extensions 20 on the wide walls of wave guide12 and extensions 20 projecting into the spaces between the side platesand the wide walls of wave guide 10.

As shown in Fig. 3 of the drawings, the ends of wave guides 10 and 12are cut back symmetrically from the center of the wide walls toward thenarrow walls to provide symmetrically beveled ends. The beveled endsprovide clearance for relative angular movement of the two guides andresult in the wide walls of the two guides being closely adjacent onlyat the center of the wide sides when the guides are in alinement. It isat these points of adjacency that the axis aa traverses the H- planecommon to the two wave guide portions.

It will be noted from the drawings that the side plates 16 on wave guide14 extend into a slot defined by the corresponding jaws 14 and outerwall extensions 24 of wave guide 12 and that similarly extensions 2% ofwave guide 12 extend into the slot between the side plate 16 and thewider walls of wave guide 19. In each instance the jaws or side plates,as the case may be, extend beyond the axis ml of the hinge sufiicientlyto provide a cover for the gap between the adjacent ends of the widewalls of the wave guide for all possible relative angular positions ofthe guides. Trunnions 22 mounted on side plates 16 of wave guide 10 arejournaled in ball bearings in jaws 14 of wave guide 12 to permitrelative rotation of the two wave guides about axis aa'.

From the foregoing it will be appreciated that while the wide sides ofthe adjacent wave guides may be separated by a considerable gap at theouter edges of the guide depending upon the-relative angular position ofthe two wave guides this gap is at all times covered by the extensions20 on the wide walls of wave guide 12. Despite this arrangement,discontinuity occurs between adjacent wide walls of the two wave guidesat the joint. Accordingly means have been provided for making the waveguide walls essentially electrically contiiuous thus preventing leakageof energy therefrom. To this end theslots formed by the side plates 16and the wide walls of wave guide 10 are so dimensioned with pect toextensions 24 of wave guide 12 as to form rgnt half wave chokes at themid-frequency of the band to be transmitted through the wave guide.

These chokes are dimensioned for maximum efi'ectiveness at the center ofthe wide walls of the adjacent wave guides at which point the extensions29 extend one-quarter wave length into the slots between the side plates16 and the wave guide Walls, the slots extending one-half wave length inall from the points of nearest adjacency of the two wave guides to theshort circuit terminations at the left hand ends of the slots. Thereduction in efficiency caused by the movement of extensions 20 in theslots between the side plates and wave guide 10 is not significant inview of the fact that the high longitudinal current concentration in'the wave guide is along the central portion of the Wide walls thereof.Regardless of the relativechoke structure which remains adjacent the gapbetween the guides at all times.

As a further precaution and for e purpose of rnizing any escape ofenergy from the guide into the'surrounding area through thespaces-between side plates 16 and extensions 20 which constitutepossible leakage paths beyond the chokes. The walls definingthe'se pathsmay be lined with a material such as polyiron which acts as-an absorberof the small amounts of radiofrequency energywhich may escape when theextremes ofangularmovement are reached. Conveniently and as shown in thedrawing such polyiron inserts 24 are mounted in the inner sides of sideplate 16 and face extensions 20 of wave guide 12 as best shown in Figs.1 and 2 of the drawings.

Although little or no longitudinal current is transmitted along thenarrow faces of wave guides 10 and 12, the gaps between these faces atthe ends of the wave guides are closed by cover plates 26 secured to thenarrow faces of wave guide 10 and bent in an arc about axis an as acenter to extend over the narrow faces of wave guide 12. These coverplates of course also serve to protect the inner elements of the hingejoint and to prevent foreign bodies from becoming lodged inside the waveguide.

Hinge joints according to the invention have been constructed for 1 /2 x3 inch wave guide to permit relative movement of -13 degrees from thein-line position. Under test such joints have been found to have astanding wave ratio of about 7 db maximum across the 12 percentband'transmitted and have not been subject to arcing across the adjacentelements of the joint for transmitter powers up to one megawatt.

What is claimed is:

l. A hinge joint connecting first and second Wave guides for relativeangular movement about 'an axis normal to an H-plane common theretocomprising a pair of side plates mounted in spaced relation on andparallel to the two wide sides respectively of said first wave guide,said side plates extending beyond the ends of said first wave guide, apair of jaws mounted on the opposite wide sides of said second waveguide and extending beyond the end thereof, extensions formed on saidwide sides of said second wave guide and with said jaws definingslotsparallel to said wide sides of said second wave guide and means pivotingsaid jaws and said side plates for relative rotation aboutsaid axis withsaid side plates received in said slots and said extensions received inthe spaces be-' tween said side plates and the wide walls of said firstwave guide.

2. A hinge joint connecting first and second wave guides for relativeangular movement about an axis normal to an pivoting said jaws and saidside plates for relative rotation about said axis with said side platesreceived in said slots and said extensionsreceived in the spaces betweensaid side plates and the wide walls of said first wave guide, and meansassociated with said joint for preventing the leakage of high frequencyenergy therefrom.

3. A hinge joint connecting first and second wave guides for relativeangular movement about an axis normal to an I-I-plane common theretocomprising a pair of side plates mountedin spaced relation on andparallel to the two wide sides respectively of said first wave guide,said side plates extending beyond the ends of said first wave guide, apair of jaws mounted on the opposite wide sides of said second waveguide and extending beyond the end thereof, extensions formed on saidwide sides of said second wave guide and with said jaws defining slotsparallel to said wide sides of said secondvwave guide and means.

pivoting said jaws and said side plates for relative rotation about saidaxis with said side plates received in said.

slots and said extensions received in the spaces between said sideplates and the wide walls of said first wave guide,

said spaces being dimensioned with respect to the portions of theextensions projecting therein to constitute chokes extending across thewide dimension of said joint to provide Wave continuity between theguides and prevent leakage of high frequency energy therefrom.

4. A hinge joint connecting first andsecond wave guides for relativeangular movement about an axis normal to an H-plane common theretocomprising a pair of side plates mounted in spaced relation on andparallel to the two wide sides respectively of said first wave guide,said side plates extending beyond the ends of said first wave guide, apair of jaws mounted on the opposite wide sides of said second waveguide and extending beyond the ends thereof, extensions formed on' saidwide sides of said second wave guide and with said jaws defining slotsparallel to said wide sides of said second wave guide, means pivotingsaid jaws and said side plates for relative rotation about said axiswith said side plates received in said slots and said extensionsreceived in the spaces between said'side plates and the .wide walls ofsaid first wave guide, and inserts of radio frequency energy absorptivematerial mounted on the inner faces of said side plates and overlappingsaid extensions to minimize the escape of radio frequency from thejoint.

5. A hinge joint connecting first and second vwave guides for relativeangular movement'about an axis normal to an H-plane common theretocomprising a pair of side plates mounted in spaced relation on andparallel to the two wide sides respectively of said first Wave guide,

said side plates extending beyond the ends of said first wave guide, apair of jaws mounted on the opposite wide sides of said second waveguide and extending beyond the ends thereof, extensions formed on saidwide'sides of said second wave guide and with said jaws defining slotsparallel to said wide sides of said second wave guides, meanspivoting'said jaws and said side plates for relative rotation about saidaxis with said side plates re-' respect to the portions of theextensions projecting there in to constitute chokes extending across thewide dimension of said joint to provide wave continuity between theguides and prevent leakage of high frequency energy therefrom andpolyiron slabs mounted on the inner faces of said side plates andoverlapping said extensions to minimize the escape of radio frequencyenergy beyond said choke.

6. A hinge joint connecting first and second wave guides for relativeangular movement about an axis normal to an H-plane common theretocomprising a pair of side plates mounted in spaced relation on andparallel to the two wide sides respectively of said firstwave guide,said side plates extending beyond the ends of said first wave guide, apair of jaws mounted on the opposite wide sides of said second waveguide and extending beyond the ends thereof, extensions formed on saidwidesides of said second wave guide and with said jaws defining slotsparallel to said wide sides of said second wave guides, means pivotingsaid jaws andsaid side plates for relative rotation about said axis withsaid side plates received in said slots and said extensions received inthe spaces between said'side plates and 'the Wide walls of said firstwave guide, said spaces being dimensioned with respect to the portionsof the extensions projecting therein to constitute chokes extendingacross the Wide dimension of said joint to provide Wave continuitybetween the guides and prevent leakage of high frequency energytherefrom, and arcuate covers mounted on the narrow faces of said firstwave guide and extending beyond said axis to bridge the gap between thenarrow faces of said first and second Wave guides for all positions ofrelative angular movement thereof.

References Cited in the file of this patent UNITED STATES PATENTS Aronet a1. Mar. 1, 1949 Kirkpatrick et a1. Mar. 24, 1953 FOREIGN PATENTSGermany Feb. 9, 1940 Great Britain May 14, 1947

